Diagnostic Accuracy of Axillary Ultrasound for Prediction of Axillary Pathologic Response after Neoadjuvant Treatment in Breast Cancer.

Abstract

Background: In the era of NAT, to accurately predict pathologic response is a great challenge, which might influence surgical approach for breast and axilla. Axillary staging via imaging methods as an adjunct have long been used with various reported accuracy rates. However, the role of preoperative axillary ultrasonography (AUS) in clinical N0 patients after NAT is still controversial. The primary goal of the present study was to evaluate the precision of preoperative AUS for identifying pathologic complete response (ypCR = ypT0, ypN0) after NAT. Methods: A single-institution, retrospective review of a prospectively maintained database was analyzed to identify breast cancer patients treated with NAT. Only those patients who underwent AUS and 18F-FDG-PET/CT before and after NAT with documentation of clinical and radiological response were incorporated for outcome analysis. Results: In 253 consecutive invasive breast cancer patients axillary ypN0 disease was achieved in 67.19%. In 11.23% ynon-pCR patients AUS failed to detect residual disease presence 80% of which were ITCs and micrometastases. Macrometastasis was present in 21.73% (55/253) of the cases 98.18% (54/55) of which was determined by AUS. Overall accuracy for axillary pCR was found to be 89.32% for AUS and 76.28 % for 18-FDG-PET/CT. The false negative rate (FNR) of AUS and 18-FDG-PET/CT was 12.04% and 15.59%, respectively. The PPV of AUS was higher in Luminal-like tumors (%87.69), whereas HER-2 positive (%100) and triple-negative (93.47%) subtypes had higher NPV. Conclusions: AUS is a beneficial tool with the potential of accurate prediction of pCR in more than 80% of patients following NAT. Nevertheless, in cases of residual ITCs and micrometastasis the accuracy of US should be interrogated cautiously.